Hundreds of protesters invaded and trashed the embassy and a second British diplomatic compound last Tuesday. British officials have said the ransacking of the embassy could only have occurred with the consent of Iran's leaders.

The raid last week led to Britain withdrawing all diplomatic staff from the country and ordering Iran to close its embassy in London.

At the embassy the items spoiled or destroyed during the raid included valuable paintings, rugs, furniture, every electronic device that could be found and several official cars. A fire also caused substantial damage.

Jewellery and other personal belongings were looted from diplomatic homes at a separate compound in northern Tehran.

A Foreign Office spokesman said: "The damage was extensive and we will be seeking compensation from the Iranian government under the Vienna convention, but it's too early to talk about precise figures."

The mob, which was several hundred strong, ripped in two a portrait of Queen Victoria by Sir George Hayter worth more than £20,000, a noted portrait artist who was a favourite of the queen's. The head was cut out of a portrait of Edward VII, while a painting of the Queen was stolen. Other works in the embassy were Tulips and Iris by Cedric Morris, worth an estimated £20,000 and Gloucester Gate, Regent's Park by Adrian Berg, one of Britain's most gifted landscape painters. Both are believed to have been lost.

The 19th century embassy in central Tehran is considered one of the finest and held the first meetings of the historic Tehran Conference at the conclusion of the Second World War.

One survivor of the incident was Pumpkin, the terrier owned by Dominick Chilcott, the British ambassador. Kept close at hand during the raid, Pumpkin was handed to friendly diplomats before the embassy staff evacuated the next day, and should be reunited with his owner soon.

Mr Chilcott has said that the operation was planned by the elements of the government and executed by the Basij, a feared semi-official paramilitary gang.

Sources in the Iranian opposition said the order for the operation had come from Supreme Leader Ayatollah Ali Khamenei himself, and was passed through the Iranian Revolutionary Guard Council to the Basij.

They claimed the ayatollah was aware of the raid's progress throughout, but backed down from initial plans to emulate the tumultuous occupation of the US embassy in 1979 after a swift and hostile international reaction.